Digital watermarking is a process for modifying physical or electronic media to embed a machine-readable code into the media, particularly for information security and data access authentication purposes. The media may be modified such that the embedded code is imperceptible or nearly imperceptible to the user, yet may be detected through an automated detection process. Most commonly, digital watermarking is applied to media signals such as images, audio signals, and video signals. However, it may also be applied to other types of media objects, including documents (e.g., through line, word or character shifting), software, multi-dimensional graphics models, and surface textures of objects.
Digital watermarking systems typically have two primary components: an encoder that embeds the watermark in a host media signal, and a decoder that detects and reads the embedded watermark from a signal suspected of containing a watermark (a suspect signal). The encoder embeds a watermark by altering the host media signal. Mostly, Random sequences are used as keys to encrypt media signals to be used as watermark during embedding processes.
The reading component analyzes a suspect signal to detect whether a watermark is present. The watermark can only be detected in the suspect signal with the help of a means that compares exactness or near exactness of the embedded watermark. The pirates of media content may try to eliminate the watermark from the media content by manipulating the media signals including audio, video, image, computer readable medium, Compact Disc (CD), hard disk, Floppy drive, and any kind of document, etc.
Hence, a need for precise watermark detection system is identified particularly for commercially distributed content (audio, video, game, etc.), to ascertain type, strength and coverage of manipulation and location of the attack.
Several particular watermarking techniques have been developed. Particular techniques for embedding and detecting imperceptible watermarks in media signals are detailed in the U.S. Pat. Nos. 6,614,914 and 5,862,260 which are hereby incorporated by reference.
However, existence of piracy is clearly a disincentive to the digital distribution of copyrighted works; establishment of responsibility for copies and derivative copies of such works is invaluable. Various forms of multimedia content, whether “master,” stereo, NTSC video, HD video, audio tape or compact disc, tolerance of quality degradation will vary with individuals and affect the underlying commercial and aesthetic value of the content. It is desirable to tie copyrights, ownership rights, purchaser information or some combination of these and related data to the content in such a manner that the content must undergo damage, and therefore a reduction in value, with subsequent, unauthorized distribution of the content, whether it is commercial or otherwise.
Hitherto, the methods of encoding and decoding of watermark known in the prior art discussed above are that, the above mentioned prior-arts have proposed typically employs correlation and frequency transform based watermark detection schemes. The digital pirates are largely inclined to use technologically advance cracking methods to defeat the security efforts taken to protect a particular media signal and particularly adopts new and unknown kinds of manipulations or distortions on the electronic media. Traditionally, these intentional distortions can be handled individually by using a template for each type of manipulation. However, when multiple manipulations occur synchronously at multiple sites of the media signals it is difficult to map each type of attack and obviously the combinations of the attack is not known, it is then it is difficult to predict the type and strength of the manipulation and design template for each such attack.
Thus there exists a need to have a robust system and method for detecting the watermark in the electronic media for each possible attacks and combinations thereof, wherein the electronic media had gone through various kinds of intentional distortions, unintentional distortions, geometrical attacks, signal processing and cryptographic attacks and the combinations of the attacks might not be known while detecting the watermarks.